Density gradient system



Dec. 31V, 1968 B. M. GusTAFsoN ET AL. 3,419,051

DENSITY GRADIENT SYSTEM Sheet Filed Nov. 17, 1966 ATTORNEYS Dec. 31,1968 B. M. GusTAFsoN ET AL 3,419,051

DENSITY GRADIENT SYSTEM Filed Nov. 17. 1966 ATToQNEYs 3,419,051 DENSITYGRADIENT SYSTEM Bert M. Gustafson, 341 Princeton, Hotlman Estates, lll.60172; Lewis Malter, 7741 Davis, Morton Grove, Ill. 60053; and Robert P.Gustafson, 7935 W. Belmont, Elmwood Park, Ill. 60635 Filed Nov. 17,1966, Ser. No. 595,199 9 Claims. (Cl. 141-69) This invention relates tomixing and dispensing liquids, and more particularly to mixing anddispensing liquids of different densities, such as gradient solutionsused to carry samples for analysis after sedimentation in a centrifuge.

Accordingly, the general object of the invention is to provide a machinefor automatically mixing and dispensing liquids, such as gradientsolutions, at a relatively high rate of production and reproducibly ascompared with prior art systems.

A further object of the invention is to provide a density gradientsystem in which the solutions are driven from separate sources to acommon mixing chamber in which the solutions are mixed after which thecombined slutions are delivered to a piercing unit collector.

Another object of the invention is to facilitate the loading of densitygradients into the respective chambers prior to mixing and to facilitatecleaning of the chambers after use.

Another object of the invention is to facilitate the quantitativepredictable non-linear as well as linear gradient systems byinterchanging various syringe pairs.

The invention also resides in a density gradient system n employing twosyringes driven at the same controlled rate to deliver the gradientsolution from one syringe to the other syringe for mixing and then fromthe latter to a collecting piercing unit.

Another object of the invention is to stir the combining FIGURE 3 is asectional view taken along the line 3 3 of FIGURE 1 showing thecarriage, its drive and controls.

FIGURE 4 is a sectional view taken along the line 4-4 of FIGURE 2.

FIGURE 5 is a diagrammatic view of the apparatus constructed inaccordance with FIGURE l.

FIGURE 6 is a view of gears shifted to drive the carriage in a reversedirection.

As shown in the drawings for purposes of illustration, the invention isembodied in a machine 10 for mixing separate liquids, such as densitygradient solutions of a light and heavier solution of sucrose, and fordispensing the combined liquids in the automatic and precise mannerneeded for density gradient solutions. The latter is the medium intowhich a sample of material is placed so that after a subsequent spinningof the sample and the gradient solution in a centrifuge, the sampleseparates and sediments at different rates in the gradient solution.After sedimentation, various layers of the gradient solution areanalyzed by radiation or chromography techniques to determine theamount, if any, of the sample in the various layers.

Patented Dec. 3l, 1968 In accordance with the present invention twodifferent liquids, such as a light and heavy Weight density solution ofsucrose, are loaded into interior chambers 11 and 12 (FIG. 5) and theliquid from one chamber is continuously forced into the other chamber inwhich the combined uids are mixed by a stirrer 13 and a predeterminedamount of combined liquids are dispensed from the mixing chamber throughan outlet 14 to a collector. Also, in accordance with the presentinvention, the constantly flowing, combined liquid is accuratelymeasured and stops limit the amount of material delivered to thecollector so that the combined fluids may be collected and filled for apredetermined amount without the careful attention of an operator.

In this instance, the chambers 11 and 12 for receiving the light andheavy liquids are in the form of cylinders disposed horizontally above asupport frame 16 and elongated cylindrical pistons 18 and 19 aredisposed partially in the cylinders and are driven at their rearwardends by a connection to a motor driven carriage 20. Herein, thecylinders and pistons are in the form of conventional hypodermicsyringes with the pistons constituting the usual plunger which isdisposed in the close fitting bore of the cylinder of the syringe.

As the plunger 18 is driven by the carriage 20 further into the cylinder11, the light weight liquid exits the cylinder through a tting 21connected to one end of a conduit in the form of a tube 22 which isconnected at its other end to an H fitting 24 leading to the interior ofthe cylinder 12. Therefore, as the plunger 18 moves to the left (FIG.1), the light fluid is forced from the cylinder 11 into the heavy liquidin the cylinder 12.

For the purpose of mixing the liquids to afford a uniform mixture forthe combined liquid being collected, the stirrer 13 stirs and mixes theliquids in the mixing chamber 25 which is the left end of the cylinder'12 (FIG. 1) immediately below the H fitting 24. Herein, the liquids arestirred while the fluid is flowing and being removed continuously fromthe mixing chamber, and to this end a T eon ball 27 with a metal rodtherein is disposed in the mixing chamber and a magnetic driver 28 isdisposed exteriorly of the cylinder and immediately beneath the mixingchamber, The driver is in the form of a T-shaped head having a pair ofmetal, magnetized arms of opposite polarity. The driver is journaled inan upper horizontal plate 30 of the frame for rotation about a verticalaxis by a driving motor 31 (FIG. 5) secured in the frame beneath thedriver. The speed and rotation of the magnetic arms of the magneticdriver is controlled by a rheostat control manipulated by a control knob29 (FIG. 1). As the motor turns the driver, the ball moves about in themixing chamber and during its movement mixes and stirs the two liquidsof different densities prior to their leaving through the outlet tube14.

To support the forward ends of the cylinders 11 and 12 in a planeparallel to the top plate 30, the forward ends of the Leur-Loks aredetachably secured to a sleeve 32 (FIG. 2) on which is formed anexterior thread a semi-spherical swivel 33 (FIG. 2) for fitting in acomplementary curved seat 34 in a plate 35 upstanding and extendingtransversely across the top plate 30 at the left end of the machine(FIG. l). To facilitate the ready attachment and disattachment of thesyringes, the seats 34 open into upwardly extending slots 36 (FIGS. land 2) and a small screw 37 (FIG. 2) is threaded to engage the verticalat rear surface on the swivel to prevent the removal of the swivel fromits seat. As indicated in the dotted lines in FIG. 2 the swivel allowsthe cylinder body to slant or deviate slightly to maintain its alinementwith the plunger as the plunger moves into the cylinder along a pathadvantageously alined with the axis of the cylinders. Thus, thecylinders and plungers are maintained in alinement to prevent breakageof the cylinders, which are usually formed from plastic or Acrylite,while affording a quick connect and disconnect support for the syringesat their forward ends. The forward ends of the sleeves 32 are formedwith a quick connect and disconnect like a Leur-Lok fitting so that therespective conduits 14 and 22 may quickly be attached or detached.

To connect the plungers 18 and 19 to the motor driven carriage 20, theright end of each of the plungers is coupled to a drive rod 38 and 39respectively, which are secured to the carriage 20. The left ends of thedriver rods are formed of reduced diameter (FIG. and fitted in atelescoping manner in a sleeve formed at right ends of the plunger head.The drive rods extend longitudinally and horizontally from the plungersto a pair of spaced horizontal bores formed in the upper portion of thecarriage and set screws threaded into the top of the carriage extend tofasten the rods to t-he carriage. The upper surfaces of the rods areformed with flats extending longitudinally along the rods for lockingengagement with heads of the set screws (FIG. 3).

For the purpose of guiding the carriage 20 for rectangular movementlongitudinally of the frame 16, a depending leg 40 (FIG. 3) of aT-shaped carriage block 41 carries a guide bushing 42 through whichextends a longitudinally extending guide rod 44 fixed in the frame. Alsoserving to guide the carriage for longitudinal movenient is a lead screw45 extending longitudinally beneath the slide rod and treaded in a nut46 seated in a U- shaped opening 48 extending upwardly from the bottomof the block. Set screws 49 and 50 are threaded from oppcsite sides ofthe T-shaped block to lock and hold the nut in the U-shaped recess. Theslide rod and the set screw are secured to the frame and are disposedparallel to one another with their respective axes in a common verticalplane, and thus, the carriage block is guided for rectangular linearmovement with the carriage moving through the elongated opening 51 (FIG.3) formed in the top plate 30.

The carriage is adapted to be driven manually with turning of a controlknob 52 (FIG. 5) fastened to the right end of the lead screw 44. Thecarriage is, also, power driven by a motor 54 (FIG. 5) connected bysuitable gearing to rotate the lead screw in either the forward or thereverse direction. As illustrated, the motor drives a gear reducer 55which drives a shaft to which is fastened a pinion gear S6. An axiallyslidable set of gears S8 and 59 are shifted between the solid lineposition of FIG. 5 for driving in the forward direction into the dottedline position for driving the carriage in the reverse direction. Whenthe gears 58 and 59 are in the lefthand position (FIG. 5) the pinion isconnected to a large gear 60 secured to a shaft 61 carrying a small gear62 to drive a gear 64 which is fixed to the lead screw to turn thelatter with rotation of the driving motor. When the gears 58 and 59 areshifted for reverse, as seen in FIG. 6, the gear 58 is connecteddirectly to the -gear 64 fixed to the lead screw bypassing the speedreduction gears and 62 fixed on the shaft 61.

To control the amount of liquid being dispensed by movement of thecarriage, a stop is provided for the carriage 20 which when engaged bythe carriage causes operation of a micro switch 66 (FIG. 5) to open themotor circuit at contacts 68 for the driving motor 54. Herein, thedepending leg 40 of the carriage block is formed with a stop finger 70extending laterally and horizontally and movable longitudinally with thecarriage to abut a stop block 71 carried on a threaded shaft 72extending longitudinally between horizontally spaced frame walls 74 and75 (FIG. 5). The ends of the threaded shaft are of reduced diameter andare journaled in the frame walls for turning with manual operation of aknob 76 fixed on the end of the shaft and extending exteriorly of theframe 16. The ends of the threaded shaft also slide axially in the framewalls when the stop block is engaged by the stop finger of the carriageand shifts the threaded shaft axially to the left (FIG. 5) to move anannular disk 7 8 xed to the left end of the shaft against a plunger 79operating the contacts 68 of the micro switch. The amount of Contactplunger movement is very small and the plunger is spring urged to aclosed position to shift disk 78 to the right when the `carriage isreturned.

To determine the position of the stop block when calculating the amountof liquid to be dispensed, the stop block 71 has an upstanding indicatorplate 80 guided in a narrow elongated slot 81 in the top plate 30. Theelongated slot extends approximately the full width of the threadedshaft so that the stop block can be moved to one position along thelength of the threaded shaft. A pointer 82 is secured by a screw to theplate 80 to indicate the position of the stop block on a scale 84 formedon the surface of the top plate.

The preferred manner of use of the invention will be described in detailhereinafter. Initially each of the syringes is removed from the machineand is lled to a desired amount as indicated by position of the plungerend relative to the indication on the cylinder. The preferred manner offilling the cylinders is to insert a needle in the Leur-Lok fitting 21or 25 and force the fluid into the cylinder. During filling of thecylinder 12, a plug is inserted into the H fitting 24. After filling thecylinders, the swivels 33 on the sleeves 32 are seated in the frontplate 35 and the retaining screws 37 (FIG. 2) are fastened. Thus, theleft ends of the cylinders are supported by the upstanding frame support35, the connection caps 85 and 86 of the plungers are then alined toreceive the telescoping ends formed on the left side of the rods 38 and39. By loosening the set screws the rods are moved forwardly and fittedin the connecting caps 85 and 86. The set screws are then tightened tolock the guide rods to the carriage.

The operator will then move the carriage 20 forward by twisting thehandle 52 and move the stop block 71 to a position to stop thedispensing after a predetermined amount of fluid is dispensed. Sinceboth the syringes in the preferred embodiment dispense fluidsimultaneously the indicator should be positioned for one half of theamount of fluid actually desired to be dispensed.

The plug (not shown) is removed from the H fitting and the connectingflexible conduit 22 is connected between the sleeve 32 for the cylinder11 and the H fitting 24 of the cylinder 12. The delivery tube 14 isconnected between the sleeve 32 for the cylinder 12 and the fitting onthe collector 15.

The operator will then operate the knob 2-9 to turn on the stirringmotor 31 which rotates the magnetic driver 28 to shift the stirrer ball27 in the mixing chamber 25 at the end of the cylinder 12. When thestirrer driver is rotating uniformly and a good stirring action istaking place, the operator turns the control knob 87 to complete thecircuit for the motor 54 which through gearing drives the lead screw 44which in turn drives the carriage 20 to move simultaneously bothplungers 18 and 19 into the respective cylinders at a uniform andcontrolled rate. The less dense fluid from the cylinder 11 moves throughthe conduit 22 into the mixing chamber 25 and is mixed by the stirrerball withthe more dense liquid and simultaneously the plunger 19 isforcing the mixed liquid outwardly through the tube 14 to the collector1S.

When the predetermined amount of combined liquid is dispensed, thefinger 70 on the carriage abuts the stop block 71 and shifts the shaft72 to the left (FIG. 5) to actuate the micro switch contacts 68 therebyopening the circuit for the electric motor. With the motor stopped noliquid is being dispensed, and the apparatus is available for the nextoperation.

The syringes may be readily cleaned to remove any remaining liquidtherein which, if it is a sucrose solution, will dry and coat thecylinders, plungers and tubes if the sucrose is not removed. Theplungers may be readily slid free from the cylinders and cleaned leavingthe interior of the cylinders exposed for cleaning.

Another manner of using the present invention is that of forcing thesample and gradient, after sedimentation, to a suitable analyzer such asa chromography analyzer. If the sample is sedimented in a sucrosesolution, each of the cylinders 11 and 12 are filled with the heaviersucrose solution. Then the motor 54 is de-energized. The sedimentedsample tube is displaced in the collector 15. Then the collector cap 88is threaded on the collector body and conduit 14 is disengaged fromconnector 32 and is replaced by a conduit to the analyzer. A needle 89formed on the end of the tube 90 is connected to connector 32. The motorswitch 87 is actuated to drive some of the solution through the outlettube 14 and into the needle 89 to bleed the lines of air. The needle 89is screwed into the fitting 91 formed on the bottom of the collector 15and is screwedupwardly until it pierces the centrifuge tube and untilthe open end of the needle moves slightly into the solution within thecentrifuge tube. With the stop block 71 set at the approximate positionfor the volume in the sample centrifuge tube, the motor 54 is operatedto drive the carriage and plungers 18 and 19 to force the solutionthrough the conduit 14 to the bottom of the centrifuge tube. Thepressure of the incoming sucrose forces the gradient solution from thecentrifuge tube out through the top of the centrifuge tube in a uniformmanner. When the centrifuge tube is completely filled with excesssolution, the carriage will actuate the stop block 71 to open the limitswitch contacts 68 and stop the motor.

From the foregoing it will be seen that with the present inventiongradient solutions may be automatically mixed and dispensed in acontrolled manner, or alternatively a gradient sample may be dispensedfrom a centrifuge tube.

What is claimed is:

1. In a -mechanism for mixing and delivering liquids, comprising thecombination of a support, a syringe on said support for receiving aquantity of a rst liquid, a second syringe on said support for receivinga quantity of a second liquid, a movable plunger in each of said firstand second syringes for forcing fluid from the syringe with linearmovement of the plunger in the syringe, a carriage connected to saidplungers for simultaneously moving said plungers to force fiuid fromsaid plungers, a conduit in fluid communication with said first andsecond syringes, a mixing chamber forming a portion of said secondsyringe for receiving said first liquid and said second liquid, amagnetic stirrer for stirring and mixing said liquids in said mixingchamber, a delivery conduit connected to said mixing chamber throughwhich the mixed liquid may leave the mixing chamber, a collector forreceiving the mixed liquid from the delivery conduit, and a motor todrive said carriage at a controlled rate to force the plungers to pushthe liquids continuously from the syringes and through the mixingchamber to the collector.

2. The combination of claim 1 including means for stopping said carriageafter a predetermined amount of movement and of displacement of liquidsfrom the syringes to the collector.

3. The combination of claim 2 in which said motor is an electric motorand in which said stopping means for the carriage includes an electricalswitch for disconnecting the drive of the electric motor from thecarriage.

4. The combination of claim 1 in which each of the syringes includes anouter cylinder disposed about said plunger, each of said cylinders beingsupported only by its plunger at one end, and a freely turnable memberconnected between the support and the cylinder at the other end of thecylinder, said member turning on said support to maintain alinement ofthe cylinder with the plunger to prevent binding of the plunger in thecylinder.

5. The combination of claim 4 wherein said carriage and said plunger areprovided with telescoping members for effecting a quick connect anddisconnect of the plungers to the carriage.

6. The combination of claim 1 including a manual drive ymeans forshifting said carriage to an initial position during a setup operationprior to operation of said motor.

7. In a device for mixing and for dispensing liquids, a support, a firstliquid chamber on said support for receiving a first liquid, a secondliquid chamber on said support for receiving a second liquid, a mixingchamber forming a portion of said second liquid chamber for mixing saidfluids, means having a passageway connecting said first chamber to saidmixing chamber, means for forcing the first and second liquids to flowsimultaneously and in equal proportions from the first and secondchambers and through said mixing chamber at a continuous controlledrate, a stirrer in the mixing chamber for stirring the liquids togetheras they move through the mixing chamber, and -means including an outerpassage connected to said mixing chamber to afford an outlet throughwhich said mixed liquids leave at a controlled rate.

8. In a machine for combining different densities and for dispensing thesame, the combination comprising, a support, a first syringe mounted onsaid support for receiving a solution of a first density, a secondsyringe on the support for holding a quantity of a solution of a greaterdensity, a conduit from the first syringe to deliver the lighter densitysolution to the second syringe adjacent a discharge end of the secondsyringe, stirring means including a member disposed in said secondsyringe adjacent its discharge end, a magnetic driver in said stirringmeans mounted on the support for driving by -magnetic force the memberinside the second syringe, a plunger in each of the respective syringesfor moving longitudinally to force the solution from the first syringethrough to the second syringe, means for simultaneously driving both ofsaid plungers at a predetermined rate to force fiuid from said firstsyringe into said second syringe and to force combined mixed solutionsfrom said second syringe, and means for stopping the driving means aftera predetermined quantity of solution is dispensed.

9. The combination of claim 8 including a stop means for stopping saiddriving means from forcing a quantity of liquid from said mixing chamberafter a predetermined quantity of liquid is delivered.

References Cited UNITED STATES PATENTS 3,242,881 3/1966 Schafer 222-145XHOUSTON S. BELL, JR., Primary Examiner.

U.S. Cl. X.R.

1. IN A MECHANISM FOR MIXING AND DELIVERING LIQUIDS, COMPRISING THECOMBINATION OF A SUPPORT, A SYRINGE ON SAID SUPPORT FOR RECEIVING AQUANTITY OF A FIRST LIQUID, A SECOND SYRINGE ON SAID SUPPORT FORRECEIVING A QUANTITY OF A SECOND LIQUID, A MOVABLE PLUNGER IN EACH OFSAID FIRST AND SECOND SYRINGES FOR FORCING FLUID FROM THE SYRINGE WITHLINEAR MOVEMENT OF THE PLUNGER IN THE SYRINGE, A CARRIAGE CONNECTED TOSAID PLUNGERS FOR SIMULTANEOUSLY MOVING SAID PLUNGERS TO FORCE FLUIDFROM SAID PLUNGERS, A CONDUIT IN FLUID COMMUNICATION WITH SAID FIRST ANDSECOND SYRINGES, A MIXING CHAMBER FORMING A PORTION OF SAID SECONDSYRINGE